Proceedings of the IAB Workshop on Stack Evolution in a Middlebox Internet,
Zurich, Switzerland,
January 2015.

Ubiquitous deployment of middleboxes has resulted in ossification of
the transport layer, with TCP and UDP becoming part of the narrow waist of
the Internet. This is a necessary stage in the evolution of the network,
caused by its progression from research, to production, to increasingly
critical infrastructure. New transport layer protocols will be needed in
future, but since we are working with essential infrastructure, we cannot
expect to have scope to make wholesale rapid changes. Future development
must be done using the existing protocols as substrates, always
maintaining on-the-wire compatibility. To advance, we must embrace the
ossification of the network, and learn to reinterpret and extend the
existing protocols.